To re-evaluate a reported association of rheumatoid arthritis (RA) with antecendent tonsillectomy or appendectomy, questionnaires were sent by post to 3673 patients who had been diagnosed as having either RA or osteoarthrosis (OA). Of those who responded 1524 were RA and 1194 OA patients. No significant differences were found between these groups with regard to the frequency of prior lymphoid surgery. This was also the case when the RA group was replaced by its rheumatoid factor (Rf) positive or Rf negative subgroup. A separate analysis of a subgroup consisting of 671 Rf positive RA patients for whom OA control subjects matched for sex and year of birth were available again showed no statistical differences in frequencies of tonsillectomy and appendectomy. Neither did partitioning the group according to the age at which lymphoid surgery was performed bring any association with an increased occurrence of RA to light. We therefore reject the hypothesis that RA is associated with antecedent tonsillectomy or appendectomy.